第一节　氧族元素1 下列关于氧族元素的叙述中,不正确的是(　　)。A .它们属于第ⅤA族元素B .随着核电荷数的增加,它们的原子半径增大C .随着核电荷数的增加,它们的非金属性增强D .单质的熔点随着核电荷数的增大而升高2 下列物质中属于同素异形体的是(　　)。A .H2 O和H2 O2 Section 1 Oxygen Element 1 The following description of oxygen elements is incorrect (). A. They belong to Group VA B. As the number of nuclear charges increases, their atomic radii increase. C. As the number of nuclear charges increases, their nonmetallicity increases. D. The melting point of the simple substance along with the nuclear charge The increase in the increase in 2 of the following substances belonging to allotropes is (). A.H2 O and H2 O2